This invention relates to improvements in the generation of polyurethane foam. More particularly, the present invention relates to improvements in the generation of polyurethane foam wherein a multi-foam gun head dispensing system is used to generate foam in a structure having a preformed configuration.
The present invention has particular application to the generation and dispensing of polyurethane foam into relatively large surface areas. For example, polyurethane foam may be used to provide insulation between building panels. Such panels may be used in the construction of relatively large buildings and comprise a shell of concrete or other building material having a core of polyurethane foam therein for insulating purposes. Such core may be considered a foam "slab". The foam slab may be generated by dispensing the foam-forming materials directly into one-half of the building panel or into a mold.
In dispensing polyurethane foam into such large surface areas, one previously known method has been to utilize a single foam dispensing gun head and allow the foam to flow to cover the area. However, the foam begins to rise into its full free-rise volume immediately upon being dispensed from the foam gun head. Thus, there has been problems with obtaining foam slabs having a uniform density throughout. In addition, the overall average density of such foam slab is higher which affects its overall economics.
In considering an automatic system for dispensing foam generating material, problems arise due to the fact that the width and/or length of two different foam slab configurations may vary by design. In addition, in some instances it is desirable to have openings in the foam slab to provide windows or doors in the ultimate panel. This adds to the problem of providing an efficient automated system.